1. Field of the Invention
The present invention relates to a system for calculating transmission utility factor value of photo energy for exposure and a method for calculating transmission utility factor value of photo energy utilizing the calculation system, and more particularly, to a system for calculating transmission utility factor value of photo energy for exposure and a method for calculating transmission utility factor value of photo energy utilizing the calculation system in which the photo energy generated from an excimer laser generator passes various optical systems (which include a lens and a reflection mirror and so on), the photo energy used for exposing a wafer is divided by the photo energy generated from the excimer laser generator and the percentage of the result is finally calculated at real time. According to the present invention, an increase of the exposing time due to the lowering of the photo transmission utility factor value and a lowering of productivity in semiconductor are prevented. According to the present invention, the badness or contamination of the optical systems between the excimer laser generator and an exposure device can be also predicted at real time.
2. Description of the Related Art
Generally, an exposure device uses an excimer laser as a deep UV light source. The light generated from an excimer laser generator is processed and transmitted by means of various optical systems (which include a lens and a reflection mirror and so on) and then passes through a mask reticle having circuit patterns. The passed light is finally irradiated on a wafer with the coated photo resist so that patterns on the mask are transferred to the wafer.
At this time, the photo energy of the light generated from the excimer laser generator is lowered according to the distance of the light path until the exposure device and the photo transmission utility factor value of various optical systems.
However, there are several disadvantages that when the light transmission utility factor value is low, the exposure device needs the light source with higher output in order to compensate the lower utility factor value, so that it causes the direct damage to the lifetime of several optical elements and when an exposure process of the wafer is performed by means of low photo energy, the exposure time is increased because of low photo transmission utility factor value and the productivity of a semiconductor is decreased.
Accordingly, it is important to monitor continuously the photo transmission utility factor value between the light source and the exposure device when exposing the wafer and to prevent the loss due to the lowering of the photo transmission utility factor value. However, there is a disadvantage that in the conventional art, the total consideration about the efficiency of the entire light path has not performed at real time.